In Backend:

1. npm init
2. npm i express
3. node index.js
4. npm i nodemon
5. change in script in package.json
6. "start" => "nodemon index.js"
7. now npm start in terminal

++++++++++++++++++++++++ in mongodb cmd:

1. show dbs (for checking is db connected or not)
2. quit() to quit

=======================

Middlewares:

1. Something in between (which is like a filter)
2. BodyParser famous middleware (It parse the request body, to handle request which comes from front-side)
3. CookieParser header and populate cookie to set cookie or check cookie
4. cors => cross origin resource sharing => outside domain then use it

================== express-validator => for validating like middleware jsonwebtoken => for authentication express-jwt

================ formidable package for multipart